1. Field of the Invention
The present invention relates to an electrochemistry apparatus, and in particular relates to an electrochemistry apparatus made of the ceramic material with high toughness and high ion conductivity.
2. Description of the Related Art
FIG. 1 shows a conventional oxygen sensor 10 comprising a first electrode 11, a second electrode 12, a chamber 13, a ceramic body 14 and a gas selective layer 15. The chamber 13 is formed in a center of the ceramic body 14. A first electrode 11 is formed on an inner wall of the chamber 13. The second electrode 12 is formed on an outer wall of the ceramic body 14. The gas selective layer 15 is coated on the second electrode 12. In gas detection, the chamber 13 is connected to an environmental gas, the environment gas reacts with the first electrode 11, and a gas to be measured passes the gas selective layer 15 to react with the second electrode 12. The oxygen consistency of the environmental gas differs from that of the gas to be measured. Thus, a voltage difference is formed between the first electrode 11 and the second electrode 12. The voltage difference generates an electromotive force to conduct the first electrode 11 and the second electrode 12 through the ceramic body 14. The oxygen consistency of the gas to be measured is obtained by measuring the voltage difference.
Conventionally, the ion conductive layer 14 is made by an injection, a dry press or an extrusion process. A conventional ion conductive layer 14 is thick with minimal sensitivity and high costs.
In the environment for testing the gas sensor 10, especially in high temperature environment, the thermal shock results in the degradation of the ceramic body 14 easily, which cause the gas sensor 10 decrease in operating lifespan and decline in function. Most of the gas sensors are shaped as a post or a plane. For example, the gas sensor disclosed in U.S. Pat. No. 6,797,138 has a structure of stacking multilayer, and is made by tape-casting or sheet thermal superimposition. The process of thermal treatment and sintering causes the gas sensor 10 warping or cracking due to the uneven contraction in different parts. US patent publication No. 2007012566A1 discloses a multilayer tubular sensor applied to detecting NiOx. The conventional multilayer tubular sensor is also fabricated by tape-casting or sheet thermal superimposition. However, the mechanical strength such as toughness or bending strength of the multilayer tubular sensor is insufficient.